1. Resources Doppler automation:
Chart with amplitude (in Pa and W/m^2 and dB) for typical sounds.
Automation of sound at molecular level dd

2. Lab Bonus There is something wrong with this animation

3. Lesson 1 What is sound and how do we plot it?
Objective: see lesson
Do Now
Define air pressure.

4. What is sound?
Wave of changing air pressure
Air pressure: Force per unit area exerted by air
Units: N/m2 = Pascal = Pa
Can air pressure be negative?
Speed of sound in air:
343 T = 20oC

5. Lesson 2: Amplitude (Volume) and pitch
Objective: Relate amplitude to volume and measure sound volume
Amplitude of sound wave = volume
Generally converted to Decibels (dB)
Define:
Sound pressure = p = amplitude of pressure wave
Pressure level = Lp = 20*log10(p/po) dB
po = 2 x 10-5 Pa

6. What is sound?
Atmospheric pressure = kPa

7. Pitch Pitch = frequency High pitch  high freq and vice versa
Which has higher frequency:
A tuba or a flute?
A fog horn or ambulance siren?
Students: Give more examples of different pitches

8. Lesson 3: Doppler Effect
Objective:

9. Lesson 4: Make up of sound
Objective:

10. Real Sound Waves Sound waves are NOT “pure” sine waves
Below is a picture of a sort of real sound wave
How could you describe this in numbers
How about this?

11. Fourier Theorem Jean-Baptiste Joseph Fourier 1768-1830
Periodic functions can be represented
as sum of sine waves…
Open the applet from:
You can move freq components up and down to see what happens to wave
Questions
Why can’t you hear the difference between th and f
How high can people hear?
CD sampling rate

12. Terms Sound is made up of waves at:
Fundamental freq: lowest frequency
Harmonics
Multiples of fundamental
Fundamental usually has largest amplitude
Relative amplitudes of harmonics determine what things sound like
Human hearing range: 20 to 20,000 Hz